US 3206227 A
Description (OCR text may contain errors)
Sept. 14, 1965 w. L. TODD, 3,206,227
7 UNDERWATER COMPLETION OVERSHOT WELLHEAD Filed March 19, 1962 7 Sheets-Sheet 1 1o T'IE 1A INVENTOR VHLLIAM L. TODD ATTORNEY Sept. 14, 1965 w, L, TODD 3,206,227
UNDERWATER COMPLETION OVERSHOT WELLHEAD ATTORNEY Sept. 14, 1965 Filed March 19, 1962 W. L. TODD UNDERWATER COMPLETION OVERSHOT WELLHEAD 134:1 I B 2A I32 '7 Sheets-Sheet 3 ue H6 /4O :2 i oo l 44b 102 104 4 I -1o4 INVENTOR WILLIAM L. TODD BY 241 M ATTORNEY Sept. 14, 1965 w. L. TODD 3,206,227
UNDERWATER COMPLETION OVERSHOT WELLHEAD Filed March 19, 1962 7 Sheets-Sheet 5 INVENTOR WILLIAM L. TODD ATTORNEY Sept. 14, 1965 w. L. TODD 3,205,227
UNDERWATER COMPLETION OVERSHOT WELLHEAD Filed March 19, 1962 7 Sheets-Sheet 6 H8- H6 H6 -1oo-\&-i2 ii INVENTOR WILLIAM L. TODD BY W ATTORNEY Sept. 14, 1965 w. L. TODD 3,206,227
UNDERWATER COMPLETION OVERSHO'I' WELLHEAD Filed March 19, 1962 7 Sheets-Sheet 7 130 M P 15 511 F IE EIB2H4 INVENTOR WILLIAM L. TODD 44 BY "55 W.
ATTORNEY United States Patent 3,206,227 UNDERWATER COMPLETION OVERSHOT WELLHEAD Wiiliam L. Todd, Houston, Tex., assignor to FMC Corporation, San Jose, Calif., a corporation of Delaware Filed Mar. 19, 1962, Ser. No. 180,650 9 Claims. (Cl. 285-3) This invention pertains to wellhead structures. More particularly, the invention relates to a casing head assembly for use in an off shore well installation of the type wherein the wellhead is at the ocean floor.
In making the usual off shore well installation of the underwater type, the casing is usually driven to substantially the desired total depth, and the casing head assembly is then welded to the casing at the surface. The casing and casing head asernbly must then be driven further down, and if the casing hangs up, it may be difiicult to force the wellhead down to the ocean floor.
The present invention relates to an underwater completion, i.e., one in which the casing head is driven to the desired depth but initially extends to the surface. A wellhead of the overshot type is then slipped down over the casing, and in conventional practice, the wellhead or casing head assembly is welded to the casing at the ocean floor. W'elding the casing head to the casing is difficult, and in some cases impossible, if the depth of the water is greater than that at which divers can work for reasonable periods of time. Underwater completions of this type are also costly, and may be dangerous to the divers.
It is an object of this invention to provide a casing head assembly of the overshot type, which may be slipped downward over the casing after the latter has been completely driven, and thereafter firmly joined to the casing at any desired depth, by manipulation from the surface.
Another object of the invention is to provide a positively acting, reliable, readily operated locking assembly for joining a casing head assembly to a casing.
Another object is to provide a casing head assembly that can be joined to a casing at the ocean floor, by a simple manipulation of the casing assembly lowering cables, or the like.
These and other objects and advantages of the present invention will become apparent from the following de-' scrlption and the accompanying drawings, wherein:
FIGS. 1A and 1B together form a vertical section through a casing head and locking assembly embodying the present invention, the assembly being shown in the process of being lowered over a casing string.
FIGS. 2A and 2B together form a similar section showing the casing head assembly after it has been joined to the casing, with a tubing hanger and tubing string installed in the casing head, and a Christmas tree afiixed thereto.
FIG. 3 is an internal fragmentary elevation taken generally at 33 of FIG. 2B showing slip mounting details.
FIGS. 4-9 are a series of schematic elevations, partly in section, illustrating the steps of completing a well using the casing head assembly of the present invention.
As previously mentioned, the casing head assembly of the present invention is of the overshot type, in that it is lowered over and secured to the casing after the latter has been placed in the ground. As will be seen as this detailed description proceeds, the assembly ratchets over the casing as the assembly is lowered, and when the assembly reaches its final position, it is given an upward tug that firmly sets it in place on the casing.
Referring to FIGS. 1A and 1B, the casing head of the present invention comprises a tubular body 12 having a vertical bore 14. The casing head includes the usual lateral wings 16 for mounting the conventional valves or pipes (not shown). Wings 16 are formed with lateral bores 18 that intersect the vertical bore 14. The lower portion of the tubular body 12 of the casing head 10 is counterbored at 20, the counterbore forming a shoulder 21. Counterbore 20 receives a casing locking sleeve assembly indicated generally at 22.
The locking sleeve assembly 22 comprises a sleeve 24 slidably received within the counterbore 20, and the sleeve 24 is limited in its upward motion in the counterbore by shoulder 21. The inner wall of the sleeve 24 is provided with an upwardly facing tapered section which forms an upwardly facing slip bowl 26. Beneath the upwardly facing slip bowl 26, the inner wall of the sleeve 24 is tapered in the reverse direction to form a downwardly facing slip bowl 28.
A plurality of hold down slips are mounted in the upper slip bowl 26 and are guided therein for vertical movement by guide pins 32 fixed to the sleeve 24 and extending through vertical slots 31 formed in the slips 30. As will be seen, slips 30 are termed hold down slips because their function is that of holding the casing head 10 down on the casing in the final, lowered position of the casing head. Each of the casing head hold down slips 30 is provided at its upper end with a T-shaped flange 34 (FIG. 3) which is slidably received in a T-shaped slot 36, formed in the lower end of an annular slip loading ring 38. The slip loading ring is slidably mounted in a bore 39 formed in the upper end of the sleeve 24. Thus the hold down slips 3!) are permitted radial movement with respect to the slip loading ring 38, as they slide along the slip bowl 26. A slip loading spring 40 is confined between the upper end of the slip loading ring 38, and a spring housing ring 42 threaded into the upper end of the sleeve 24. The slip loading spring 40 applies a downward pressure upon the hold down slips 30, to maintain them in resilient engagement with the outer surface of the casing 44, on which the casing head 10 is to be eventually supported.
A plurality of easing head hold up slips are slidably mounted in the lower slip bowl 28, and are guided therein for vertical movement with respect to sleeve 24 by guide pins 52. These pins are fixed to the sleeve 24 and extend through slots 54 formed in the hold up slips 50. Slips 50 are termed hold up slips because their function is that of holding the casing head up on the casing, that is they transfer the weight of the casing head to the casing, when the casing head is in its final, lowered position. Teeth 50a of the hold up slips 50 are shaped to bite into the casing under forces that tend to move the casing head assembly down along the casing. Each hold up slip 50 is initially keyed to sleeve 24 by a shear pin 56, which extends through matching openings in the slip 50 and the sleeve 24. At initial assembly of the parts, shear pins 56 retain the slips 50 in their lowermost position in the bowl 28, so that the hold up slips clear the casing and hence permit the casing head to be lowered along the casing. A hold up slip setting [ring 60 is screwed into the lower end of the body 12 of the casing head, and the upper end of the ring 60 abuts the lower ends of the hold up slips 50, with the upper end of the sleeve 24 abutting shoulder 21 formed by the counterbore 20. A set screw 62 locks the slip setting ring 60 in its adjusted position.
Means are provided to finally support the Weight of the tubular body 12 and the casing head on the looking sleeve 24 (which is ultimately locked to the casing by the slips) while accommodating a short upward motion of the casing head vrelative to the locking sleeve 24, in order to set the hold up slips 50. For this purpose, sleeve 24 is formed with an upwardly facing taper 72, and locking wedges 74 are retained against the taper by guide pins 76 threaded into the sleeve 24. Pins 76 ride in slots 78 formed in the locking wedges 74. A locking wedge compression spring 80 is confined between the upper end of each wedge 74 and a shoulder 81 formed on sleeve 24. The springs 80 urge the wedges 74 toward their lowermost position, into wedging engagement "between the sleeve 24 and the body 12 of the casing head. The inner Wall of the body 12 of the casing head is formed with a shallow downwardly facing tapered surface '82 to prevent the wedges 74 from jamming when the body 12 is moved upward with respect to the sleeve 24, during the final slip setting operation to be described.
' In order to hold the locking sleeve assembly 22 in its upper position in counterbore 20 against shoulder 21 while the slip setting ring 60 is being screwed in place, and in order to protect the hold up slip shear pins 56 from being prematurely sheared, a master shear pin 86 is mounted in bores in the body 12 and the sleeve 24, with the sleeve 24 in its uppermost position relative to the body 12. As illustrated in FIG. 1B of the drawings, shoulder 21 transfers the force from the casing head to the locking sleeve 24 that is necessary to slip the sleeve assembly 22 down along the casing against the frictional resistance offered by hold down slips 30.
The order of assembly of the parts will now be described. The T-shaped flanges 34 on the hold down slips 30 .are first slipped into the T-shaped slots 36 in the slip loading ring 38. The hold down slips 30 and the loading ring are then placed in position in the upper slip bowl 26 in the sleeve 24, and the guide pins 32 are installed to retain the slips in the upper slip bowl. The slip loading spring 40 and the spring housing ring 42 are then installed. The hold up slips 50 are then installed in the lower slip bowl 28, and the retaining and guide pins 52 are fitted to maintain the hold up slips in the lower slip bowl. The hold up slip shear pins 56 are then installed to releasably retain the hold up slips 50 in their lowermost positions in the bowl. As illustrated in FIG. 1B, in this position the casing head hold up slips will clear the casing 44, and permit the casing head to be lowered along the casing.
The locking wedges 74 and their actuating springs 80 are then installed on taper 72 of the locking sleeve, and the guide pins 76 are installed to retain the locking wedges 111 place. The wedges :are forced to their uppermost posit1on,.and temporary assembly pins 89 (shown in phantom in FIG. 1B) are installed in matching lateral bores 90 and 92 in the wedges 74 and the sleeve 24, respectively. These pins temporarily retain the wedges in their uppermost positions, which will be slightly above their position illustrated in FIG. 1B. The wedges will now plear body taper 82 slightly, and this slight clearance is necessary in order to permit the locking sleeve assembly to be freely slid upwardly into counterbore 20 of the tubular body 12, .and against the shoulder 21. The sleeve 24, with the parts already assembled thereon, is then installed within the counterbore of body '12 as indicated in FIG. 1B, and the master shear pin 86 is installed, to releasably retain the sleeve 24 in its uppermost position relatlve to the body 12. The hold up slip setting ring 60 is then screwed into the lower end of the body 12 until its upper end engages the lower ends of the hold up slips '50. The locking set screw 62 is then installed to retain the hold up slip setting ring 60 in its final position. The locking wedges 74 can now be released to engage body taper 82, as illustrated in FIG. 1B. To release the wedges, the projecting ends of pins 89 are grasped and the pins are removed from the matching bores 90 and 92, to permit looking wedge springs 80 to move the locking wedges 74 downward slightly, so that wedging contact is established between the difierentially tapered surfaces 72 and 82 of sleeve 24 and body 12, respectively.
As can be best understood from FIG. 1B, the casing head assembly can now be lowered along the outer surface of the casing 44. Hold up slips 50 clear the casing during lowering, and the teeth 30a on the casing head hold down slips 30 are shaped so that they are self releasing, and hence do not bite into the casing 44 as the casing head assembly is passed down over the casing.
When a casing collar 44a is encountered, the collar will temporarily restrain the hold down slips 30 from their motion with the locking sleeve 24, against the force of the hold down slip loading spring 40. Since the locking sleeve 24 continues its downward motion, the larger diameter portion of tapered bowl 26 moves over the slips, which provides sufiicient clearance to permit slips 30 to move radially outwardly a sufficient distance to pass the casing collar. As soon as the collar is passed, the slip loading spring will move the slips 39 downward again into resilient, non-biting contact with the outer surface of the casing 44.
When the casing head 10 has been lowered to its final position, the casing head hold up slips 50 must be set, to lock the locking sleeve 24 to the casing. In order to set the hold up slips 50, an upward pull is exerted on the casing head by means of the lowering cables (not shown in FIGS. 1A and 1B). The casing head is thereby urged upwardly, causing the tecth 30a of the hold down slips 30 to bite into, and tightly grip the casing 44. This prevents upward movement of the sleeve 24 on the casing. On application of sufficient lifting force to the casing head, the master shear pin 86 breaks, and the body 12 of the casing head can now be raised relatively to the sleeve assembly 22. Since the hold up slip setting ring 60 was screwed against the bottom of hold up slips 59, this additional lifting eiiort also breaks the hold up slip shear pins 56. Continued lifting of body 12 soon brings the hold up slips 50 into wedging contact with the surface of the casing 44, that is, to the position illustrated in FIG. 2B. As mentioned, the teeth 50a on the hold up slips 50 are shaped to bite into the casing 44, and once set slips 50 will resist downward motion of the sleeve assembly 22 along the casing 44. The lock- 7 ing sleeve 24 is now firmly locked to the casing against motion in either direction.
Because of the differential tapers 72, 82, the locking wedges 74 are self-freeing during the lifting action on the casing head required to set the hold up slips 50. However, as the casing head is lifted relative to sleeve 24, the wedges 74 are moved downward by the springs 80, and thus maintain their snug engagement with both tapers 72 and 82. The wedges 74 will not permit downward motion of the casing head relative to sleeve 24, so that when the lowering cables are released, the wedges transfer the weight of the casing head to the locking sleeve 24. Since, as previously described, sleeve 24 is itself supported on the casing against downward motion by the hold up slips 50, which are now firmly set in engagement with the outer surface of the casing, the casing head and locking sleeve assembly are now firmly supported by the casing. As seen in FIG. 2B, a shoulder 61 formed on the hold up slip setting ring 60, is now in engagement with the lower end of locking sleeve 24. Thus any forces tending to lift the casing head are transmitted directly to the locking sleeve 24. These forces are, in turn, transmitted by the locking sleeve 24 to the casing by means of the hold down slips 30. Thus the casing head 10 and locking sleeve assembly 22 cannot be forced up along casing 44, because of the wedging, biting action of the teeth 30a of hold down slips 30 against the casing.
The overshot casing head having been installed on the casing, the completion of the wellhead assembly will now be briefly described. A casing cutter is run into the casing 44 and the projecting portion of the casing is cut oil at 44b (FIG. 2A), so that the casing terminates within a lower portion of bore 14 in the casing head. A sealing sleeve 100, having bores 101 that match lateral bores 18 formed in the casing head, is then run into the bore 14 of casing head. Inner and outer seals 102 and 104 carried by sleeve 108, seal off the open lower end of the casing head from the upper end of the casing 44, as well as sealing off the open lower end of the casing head from the bores 18 in body 12 of the casing head. Spring latches 106 are mounted on the sealing sleeve 100, and these snap into an annular groove 108 provided on the inner wall of the casing head 10, to retain the sealing sleeve in its installed position. The wellhead assembly is now ready for mounting of the tubing string, Christmas tree, and other equipment.
The steps of forming a well using the overshot wellhead assembly of the present invention will now be explained with reference to FIGS. 4 through 9. First a surface bore B is drilled in the ocean floor F, from a floating drilling barge, or other drilling structure, using any of several well known techniques for underwater drilling. The casing 44 (FIG. 4) is installed, either by following the bit while drilling the bore, or after the initial bore is completed. The casing 44 is then cemented in place by passing cement C down through the casing in the conventional manner.
The casing head assembly is then lowered over the casing 44 in the position illustrated in FIG. 5, using a lowering cable sling D, or the like. The usual stage or platform P will preferably have been welded to the casing head body 12, and lateral valves V, or the like, will have been bolted to the wings 16. The casing head assembly is locked to the casing by exerting an upward tug on the lowering cables, in the manner previously described in detail. As was also previously described, a casing cutter (not shown) is lowered through the casing and the casing is cut off at 44b, as illustrated in FIG. 6. The severed upper casing section (not shown in FIG. 6) is lifted clear of the casing head. Valves V do not appear in FIG. 6, nor in FIGS. 79. A blowout preventer assembly 112 is then lowered and clamped to the upper end of the casing head 10, by a remotely controlled split, pivoted clamp 114. The clamp 114 is C-shaped in cross section, and embraces mating radial flanges 116 and 118 formed on the casing head and the blowout preventer 112, respectively.
As previously described and as further illustrated in FIG. 7, the sealing sleeve 100 is then lowered (by means not shown) through the blowout preventer 112 and into the casing head 10. The sealing sleeve 100 latches itself in place. The drill pipe (not shown) is then lowered through the blowout preventer 112, the casing head 10 and the casing 44, and drilling is continued until the production bore is driven to the desired depth.
After the production bore has been drilled to the desired depth, the drill pipe is removed and the production tubing string 120 is installed, as illustrated in FIG. 8. The tubing string is suspended from a tubing hanger 122, which hanger is received within the sleeve 100. A beveled lower edge 124 of the hangar rests on an upwardly facing frusto-conical seat 126 formed on the sealing sleeve 100. A nipple 128 is screwed into the upper end of the tubing hanger 122. The blowout preventer 112 is now removed, by releasing the remotely controlled clamp 114, and a Christmas tree assembly 130 is lowered and clamped in its place, as illustrated in FIG. 9. The lower end of the Christmas tree 130 is provided with a radial flange 132 which cooperates with the flange 116 on the casing head 10 for attachment by the clamp 114. The bore 134 in the Christmas tree 130 slidably embraces the nipple 128, and a pair of O-ring seals 136 and 138 mounted in grooves 140 and 142, respectively, in the Christmas tree, effect sealing engagement of the Christmas tree bore 134 with the nipple 128. This completes the basic wellhead installation.
While a preferred embodiment of the invention is described herein, it should be noted that various changes may be made therein without departing from the spirit of the invention as defined in the appended claims.
The invention having thus been described, what is believed to be new and is desired to be protected by Let-- ters Patent is:
1. An overshot wellhead comprising a casing head having a tubular body, a locking sleeve slidably mounted in said tubular body, oppositely facing upper and lower slip bowls formed in said locking sleeve, a plurality of easing head hold down slips mounted in said upper slip bowl, a plurality of casing head hold up slips disposed substantially entirely in said lower slip bowl, said hold down slips and said hold up slips being so constructed and arranged as to be adapted to engage a casing received within the locking sleeve, means for resiliently urging said hold down slips downwardly in their slip bowl for resilient engagement with a casing positioned in said body so as to preclude upward movement of the sleeve on the casing, as the casing head is lowered along the casing, means releasably supporting said hold up slips in their slip bowl, free of gripping engagement with the casing as said casing head is lowered, means on said tubular body for lifting the hold up slips into gripping engagement with the casing upon short upward movement of the easing head thereby to lock said locking sleeve against downward movement on the casing, and wedge means between said locking sleeve and said tubular body for supporting the body on said locking sleeve, said wedge means accommodating the upward motion of said casing head relative to said locking sleeve required to lock said hold up slips to the casing.
2. The wellhead of claim 1 wherein the locking sleeve has an upwardly facing taper confronting the body, and wherein the body has a downwardly facing taper confronting said upwardly facing taper, wherein said wedge means is positioned between and in engagement with said tapers, and wherein said wedge means includes a block and a spring urging the block downwardly along said tapers.
3. An overshot wellhead comprising a casing head having a tubular body adapted to fit over a casing, a locking sleeve slidably mounted in said body in surrounding relation to such a casing, oppositely facing upper and lower slip bowls formed in said sleeve with the upper bowl diverging upward and the lower bowl diverging downward, casing head-hold-down slips mounted in said upper bowl, casing head-hold-up slips in said lower bowl. said hold-down and hold-up slips being so constructed and arranged as to be capable of engaging such a casing. means penetrating said sleeve which releasably precludes movement of said hold-up slips in their bowl and thereby maintains said hold-up slips free of gripping engagement with the casing as the casing head is lowered, means on sa d body engaging said hold-up slips for lifting the same into gripping engagement with the casing upon short upward movement of the casing head so that the sleeve is supported on the casing by the hold-up slips, and means for supporting said casing head on the sleeve.
4. The wellhead of claim 3 wherein said penetrating means are shear pins interconnecting said hold-up slips and said lower bowl.
5. The wellhead of claim 3 wherein said engaging nlieans abuts and is axially separable from said hold-up s ms.
6. The wellhead of claim 3 wherein said sleeve has a lower end portion within which said lower bowl is formed, wherein said penetrating means maintains the hold-up slips substantially entirely within the lower bowl, wherein the engaging means is a ring connected to the body and pro ect1ng upward into abutment with the hold-up slips, and wherein said ring is inwardly circumferentially spaced from the body so as to receive the lower end por t1on of the sleeve upon said short upward movement.
7. The wellhead of claim 3 wherein the slips have slots extending longitudinally thereof, and wherein guiding pins project from the sleeve into the slots for precluding movement of the slips circumferentially of their respective bowls.
8. In combination, a casing head having a tubular body provided with a lower end, an internal wall projecting upward from said lower end, and an upper shoulder projecting inward from said wall; a setting ring having a lower shoulder connected to the internal wall of the body adjacent to its lower end and flange means projecting upward from the lower shoulder in circumferentially spaced relation to the internal wall; a locking sleeve having upper and lower end sections within which are respectively provided upwardly divergent and downwardly divergent slip bowls, the sleeve being axially slidably fitted within the body for movement between an upper position with the upper end section in abutment with said upper shoulder and a lower position with said lower end section in abutment with the lower shoulder; means releasably retaining the sleeve in said upper position; upper slips mounted in said upper bowl; and lower ,slips positioned within the lower bowl in abutment with flange means of the setting ring said slips being so constructed and arranged as to be adapted to engage pipe received within the locking sleeve.
9. In combination, a casing head having a tubular body provided with an internal wall; a locking sleeve fitted within the body having an external wall engaging the internal wall of the body, said sleeve also having an internal wall, said internal wall of the sleeve including a downwardly divergent lower slip bowl, an upwardly divergent upper slip bowl, and a substantially cylindrical upper portion projecting upward from the upper bowl; upper slips disposed in the upper bowl; a spring housing having an upper end connected to the sleeve and a tubular portion projecting downward in circumferentially spaced relation to the upper portion of theinternal wall of the sleeve, the housing and sleeve defining an annulus therebetween; a slip-loading ring axially slidably fitted in the annulus, the upper slips having means mounting the slips on the loading ring for relative radial movement therebetween; spring means in said annulus for yieldablyurging said ring downward; lower slips disposed within the lower bowl; said upper and lower slips being so constructed and arranged as to be adapted to engage. pipe within the locking sleeve; and means for actuating the lower slips into engagement with such pipe. 7
References Cited by the Examiner UNITED STATES PATENTS 785,105 3/05 Johnston 294-8631 1,243,904 10/17 Wagner 16698 2,551,240 5/51 Bonner 24263.5 2,593,725 4/52 Brown 285144 2,683,492 7/54 Baker 24-2635 2,887,754 5 59 Johnson. 2,970,646 2/61 Knapp 16645 3,032,106 5/62 Focht 166 -46 3,071,188 1/63 Raulins. 3,090,640 5/ 63 Otteman 285-3 3,134,610 5/64 Musolf 285 -3 FOREIGN PATENTS 583,025 10/58 Italy.
CARL W. TOMLIN, Primary Examiner.